Why does my TV click then shut off if tilted forward or backward?

If I tilt my TV forward or backward it makes a click sound then shuts off and won't come back on unless I either tilt it again or unplug and plug it back in. This really wasn't an issue as long as it wasn't moved HOWEVER a while ago it did this but when I got it turned back on the TV will not respond to the remote or the buttons on the front of the TV. There is a good picture AND sound although it's very low but I cannot change the channel, turn volume up or down, bring up the menu, turn it on or off, or ANYTHING else. The remote sensor light on the front of the TV blinks when I press a button on the remote so I know it's trying to communicate but can't. Is it a bad capacitor on the power board? Or something else? Please help. It was given to me and it's got a great picture so I would really like find out what it is. It's an LG 50PX2DC-UD Plasma (50 inch I think).